#include <fstream>
#include <iostream>

using namespace std;

int main()
{
    int n,phi[1000000];
    long long total=0;
    ifstream in("fractii.in");
    in >> n;
    in.close();
    for (int i = 2; i <= n; ++i)
        phi[i] = i-1;
    for (int i = 2; i <= n; ++i)
    {
        for (int j = 2*i; j <= n; j+=i)
            phi[j] -= phi[i];
        total+=phi[i];
    }

    ofstream out("fractii.out");
    out << 2*total + 1;
    out.close();
    return 0;
}